Lubricating compositions

ABSTRACT

New lubricating compositions are characterized in that in addition to the basic oil, they contain an organic sulfur compound which is a heterocyclic disulfide, which can contain sulfide moieties, containing not more than one carbon atom between heterocyclic sulfur atoms. The lubricating oils are useful as high pressure oils.

United States Patent 1191 Labat et al. Dec. 23, 1975 [54] LUBRICATING COIVIPOSITIONS 2,213,804 9/1940 Lincoln et al 252/45 2,744,070 5/1956 Baker et al. 252/45 X [75] lnvemors- Yves Lab, 9" f 2,891,072 6/1959 Remes et al. 252/45 x Chuzelles; J Baptiste Slglwul'et, 2,900,392 8/1959 Remes et al. 252/45 x Pau, all of France 2,941,945 6/1960 Fainrnan et a1. 252/45 x Assigneez Entreprise de Recherches et 2,966,521 12/1960 Webb 252/45 X dActivites Petrolieres (ELF), Paris, France Primary Examinerl-lelen M. S. Sneed [22] Filed: Oct- 10, 1973 gigggzley, Agent, or Firm-Ostrolenk, Faber, Gerb & [21] Appl. No.: 404,887

[30] Foreign Application Priority Data [57] ABSTRACT Oct 19, 1972 France 72.37129 New lubricating compositions are characterized in that in addition to the basic oil, they contain an or- [52] US. Cl. 252/45 ganic sulfur compound which is a heterocyclic disul- [51] Int. Cl. ..C10M 1/38;C10M 3/32 fide, which can contain sulfide moieties, containing [58] Field of Search 252/45 not more than one carbon atom between heterocyclic sulfur atoms. The lubricating oils are useful as high [56] References Cited pressure oils. UNITED STATES PATENTS 10 C N D 1,805,052 5/1931 Sebrell 252/45 0 rawmgs LUBRICATING COMPOSITIONS BACKGROUND OF THE INVENTION The problems in the field of lubricants have been known for a long time. The tendency of manufacturers to conceive and create smaller and smaller mechanisms functioning under conditions of greater and greater severe charge, speed and temperature makes the role of lubricants more and more difficult. This is particularly the case for lubricants which are utilized in apparatus or machinery in which the metallic pieces undergo the important phenomena of friction.

The use of organic or synthetic mineral oils for the lubrication of different kinds of metals which rub together has been known for a long time, however, the use of virgin oil is not without its inconveniences. They do not completely prevent corrosion and they can create secondary oxidation phenomena with the formation of muds, and, eventually, hard hydrocarbon products which deteriorate the metal pieces which they contact.

Recourse to multiple usage lubricants, and, particularly, to lubricants possessing high pressure qualities and remaining non-corrosive with respect to copper metals is becoming more and more necessary in numerous enterprises, especially for economic reasons. Many solutions have been proposed to improve the lubrication properties of oils or lubricants and to allow them to respond favorably to a certain number of required tests specific to the diverse utilizations.

The characteristics and properties of lubricants currently in commercial use vary considerably as a function of their desired application. One of the best solutions to the foregoing problems is the addition of additives to the oils. The additives are chemical products in various quantities, incorporated in the lubricants to modify the physical, chemical or mechanical properties. The composition of these additives differs according to the desired properties of the oil for the intended use. Thus, for example, additives for high pressure lubricants should improve the oil-metal contact by modifying the characteristics of the oil or chemical modification of the metallic surface. These high pressure additives are used to formulate oils or greases for the lubrication, for example, of gears, hypoidal couples, machine tools, smooth bearings or highly charged rolling mechanisms.

The oil additives are essentially constituted by compounds containing sulfur, phosphorus or chlorine. Under the conditions of use, a film of metallic sulfur, phosphorus or chlorine is formed on the exposed surface of the machinery and these films allow avoidance of the mechanical deterioration mentioned above.

Among these additives, those which contain sulfur in the form of organic compounds are the most often used. Basic studies relative to the possible use as additives for lubricating compositions of various linear organic polysulfides [R-(S-h-R'] have shown in actual usage tests that the high pressure qualities of the polysulfides improve with an increase in the x. On the other hand, however, copper corrosion increases very rapidly as x of the polysulfide increases. It is difficult to avoid the corrosion using polysulfides where x is greater than 2. On the other hand, it has been shown that additives possessing C-S bonds have an activity less than that of additives containing 8-8 bonds. The compounds actually known as high pressure additives are linear compounds in which the sulfur is generally present in the 2 form of a disulfide. Further, as pointed out in British Pat. No. 1,215,174, only certain disulfides increase the load carrying capacity of lubricating oils to any marked degree.

It has been found that certain very specific heterocyclic sulfur compounds have utility in high pressure oils. The aforementioned British patent teaches that compounds of the formula are so useful.

Lincoln et al, U.S. Pat. Nos. 2,213,804 and 2,292,456 teach that certain stable heterocyclic organic compounds containing at least two sulfur atoms in the ring, such as 1,3,5-trithiane and its derivatives such as trithiobenzaldehyde, 1,4- and 1,3-dithiane, trimethylene-l,2-disulfide, dithiazolidine and its derivatives such as phenyl thiuret and dithiodiazole and its derivatives such as thionyl pseudo thiocarbazone, can be used.

In Baker et al, U.S. Pat. No. 2,744,070, a dimer be lieved to be is produced by reacting a non-conjugated olefin of at least 6 carbon atoms with a sulfur halide at a temperature of about 0-50 C. to form a di(haloalkyl) sulfide intermediate, and at once condensing the intermediate with a water-soluble inorganic higher polysulfide at a temperature of about 50-l00 C. in a mutual solvent.

It has been very regrettable to be obliged to use sulfur additives limited to low sulfur content because of the corrosion effect while knowing that a higher sulfur concentration confers better lubricating properties to the oils.

The present invention resolves this sulfur content problem. The invention is based on the concept of increasing the sulfur concentration by the presence of various kinds of disulfides and/or sulfides in the same organic molecule and not by increasing the sulfur chain, the solution looked to till now by those skilled in the art.

SUMMARY OF THE INVENTION This invention relates to a new lubricating composition and more particularly to a new lubricating composition containing a heterocyclic sulfur additive which is a heterocyclic compound of disulfide and/or sulfide moieties and containing no more than 1 carbon atom between sulfur atoms in the heterocyclic ring.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the present invention, the principal constituents of the new lubricating compositions are the organic or synthetic mineral oil and one or more sulfur additives which are a heterocyclic compound of disulfide and/or sulfide moieties in which the heterocyclic sulfur atoms are separated by at most 1 carbon atom.

The heterocyclic compounds used in the instant invention contain one or more (which need not be the same) disulfide moieties and one or more (which need not be the same) sulfide moieties The disulfide and sulfide moieties can be arranged consecutively or alternately. Preferred heterocyclic compounds are of the formula -C). CM. :1

R R R and R which can be the same or different, are hydrogen, alkyl or alkenyl radicals of 1-6 carbon atoms; R and R and also R and R,,, can respectively form with the carbon atom to which they are joined a saturated or unsaturated ring of 4-8 carbon atoms; n is l-4; m is 0-4; and the alkyl, alkenyl, cyclanic and cyclenic groups can contain hetero atoms such as sulfur.

Within the framework of the present invention, suitable compounds are derived from tetrathiane heterocyclics such as 3,3,6,6-tetramethyl-l ,2,4,5-tetrathiane, 3,6-dicyciohexyl-l,2,4,5-tetrathiane, 3,3,6,6-tetravinyl-1,2,4,5-tetrathiane, as well as compounds derived from trithiolane heterocyclics such as 3,5-dicyclobexyl- 1,2,4-trithiolane and the like.

Products derived from 2,3,5,6,7-pentathiapanes are less suitable because they contain the trisulfide system and even though they have good high pressure properties, they are corrosive to copper metal.

The sulfur heterocyclic additives of the preceding formula can be-prepared according to known methods described in the literature.

The oils used in the present compositions can be mineral oils obtained by different processes of refining, e. g., treatment with solvent or hydrorefining. These oils are not constituted by only one hydrocarbon but are said to be paraffms, naphthalenes or aromatics with one or another of these hydrocarbons in major proportion.One can equally use organic oils or synthetic oils such as alkylbenzene, esters and polyglycols.

The quantity of heterocyclic additive introduced into the oil for improving the lubricating properties can vary within quite large limits and varies according to the use to which the lubricant is destined. Generally, the lubricant oils contain 0.5-15%, preferably 0.75-7.5%, by weight of heterocyclic additive and 99.5-%, preferably 99.25-92.5% of oil.

The lubricating oil compositions are prepared by mixing the oil and the heterocyclic additive at a temperature generally between 50-100 C. with agitation, preferably between 60-80 C.

Complementary adjuvants can be added under the same conditions in order to impart a particular quality or complementary property to the composition. Such adjuvants can be, e.g., antioxidants, anticorrosives, viscosity controllers, antifoam additives, de-emulsifying agents, anti-usages, detergents and dispersants.

Lubricant compositions undergo a series of laboratory tests before industrialization which are designed to simulate the problems or conditions encountered in actual use. Being specially designed for high pressure oils, the additives of the present invention are studied in the following tests: high pressure 4 ball machine (norm ASTM D 2596 or norm FS 6503), machine FZG (norm DIN 51354), machine Timken (norm ASTM D 2509), and copper corrosion test (norm NF M 07-015).

In order to more fully appreciate the improved qualities of the new lubricating compositions, the Tables below present the results of the corresponding tests of lubricant compositions according to the invention as well as those corresponding to known lubricant compositions. The particular requirements for a given application is also indicated.

EXAMPLE 1 parts of a synthetic alkylbenzene oil and 1 part of tetramethyl tetrathiane (TMTT) and 0.5 part of an amine anticorrosive agent were placed in a receptacle which was heated to 60 C. and strongly agitated. The resulting composition was subjected to a series of tests. The composition possessed the qualities required by the French Navy for use in the lubrication of refrigera- TABLE I LUBRICANTS FOR COMPRESSORS (Norm Marine STM 7272) Characteristics Specifications Base Synthetic +1% Commercial Base Synthetic dibenzyl Base Synthetic 2% TMTT disulflde Alone 0.5% anti- 0.5% anti- (Alkyl Benzene) corrosive corrosive Copper Corrosion NF M 07-015 TABLE I-continued LUBRICANTS FOR COMPRESSORS (Norm Marine STM 7272) Base Synthetic +l% Commercial Base Synthetic dibenzyl Base Synthetic 2% TMTT disulfide Alone i- 0.5% anti- 0.5% anti Characteristics Specifications (Alkyl Benzene) corrosive corrosive 3 hours-100 C. lb max. 1 a lb lb Sea Water Corrosion Test of ASTM D 665 Method B Pass Fail Pass Pass Hertz Charge FS 6503 4-ball machine 22.5 daN I7 55 37 Stability in the Presence of Dichorodifluoromethane; HCl formed I g HCl 0.2 1.57

The oil re ared in this Exam le can be used in aero- EXAMPLE 2 P P P Following the procedure of Example 1, a lubricating composition was prepared using paraffin-type mineral oil and 2% of TMTT. The resulting oil possessed excellent high pressure qualities and as indicated in Table II, performed favorably in the charge capacity test without copper corrosion or sedimentation at low temperature. The Table also shows the results of tests made with 2% dibenzyl disulfide for comparison.

TABLE II High Pressure Mineral Oil (Norm AIR 3525A) nautical technical service for lubrication of gears.

EXAMPLE 3 A lubricant composition was prepared as in Example 1 using a paraffin-type mineral oil and 5% of TMTT with and without 0.05% of a copper corrosion inhibitor. Test results are shown in Table III and compared with the same oils containing a sulfur-containing polybutene. The compositions of the present invention give Base Mineral Base With 2% Mineral Commercial Specifi- With 2% Dibenzyl Characteristics cations Norm TM'I'I Disulfide Precipitation Index 0.1 AIR 165l/A pass pass Charge Capacity 40 AIR 1650/A 55 Copper Corrosion (100 C 72 H) 2e NF M 07-015 2b 4b Storage 20 C. no sedimentation AIR 1651 [A pass fail lubricants which can advantageously be employed for industrial gears.

i TABLE III LUBRICANTS FOR INDUSTRIAL GEARS Base Oil 5% Commercial Base Oil Sulfur-con- Base Oil 5% Commercial taining Poly- 5% TMTT Sulfur-conbutene Base Oil 0.05% Copper taining poly- 0.05% Copper I Test I Speciflcationis 5% TMTT Inhibitor butene Inhibitor thermal Holding at 150 C. Amount of Air 5 L/h-I68I-I Presence of Steel XC 18S Bronze Variation of Viscosity 45 40 94 I20 Variation of Acid Index 3 L20 1.0 2 2' Loss of Weight of Steel, mg/cm v 0 0 0 i 0 0 Loss of Weight of Bronze, mg/cm 0 4.2 0 .-30.4 33.9 Copper corrosion (NF M 07-015) 3 hours at 100 0. lb max. 16 lb 2a 1b 72 hours at 100 C. 2e max. 2b lb 4b 4 Charge Capacity I 4-Ball Machine (FS 6503) Seizing (kg) 80 min. 80 80 80 80 Solder (kg) 315 min. 600 600 400 400 Average Hertz Charge 45 min. 80 80 65 Timken Machine (D2509) 40 min. 40 40 40 40 OK Load (lbs) Machine FZC (DIN 51354) I N Normal Speed bearing13 m I3 l3 12 12 Double Speed bearing 10 mini 10 I0 8 8 EXAMPLE 4 Lubricant compositions were prepared by mixing a paraffin-type base oil having the following characteristics: 200 NS (neutral solvent), viscosity 200 S/Saybolt Universal at 100 F., and 3% of an additive of the present invention or 3% of a prior art additive, as in Example 1. Each lubricant composition was tested on the 4-ball machine, norm FS 6503. One thus determines the charge before seizing (or L.N.S.L.(kg)), the charge of solder (or W.L.) and the average Hertz charge (or W.L.l.). Copper corrosion tests for 3 and 72 hours were also conducted. The results are shown in Table IV and show that the lubricants of the present invention possess particularly interesting properties in comparison with the prior art high pressure lubricant oil.

TABLE IV 2. The composition of claim 1 wherein said heterocyclic compound is of the formula comprises employing as the additive a heterocyclic compound consisting of 4 Ball Machine Norm FS 6 J 03 Additive L.N.S.L. (kg) W.L. (kg) L.W.l.

Copper Corrosion Test Norm AFNOR M 07015 Tgramcthyl tetratgiane C 3 S CH Various changes and modifications can be made in the process, additives and compositions of this invention without departing from the spirit and the scope thereof. The various embodiments set forth herein were for the purpose of further illustrating the invention but were not intended to limit it.

We claim:

1. A high pressure lubricating oil composition comprising oil and as an additive therefor, a heterocyclic compound consisting of groups arranged consecutively or alternatively with groups to form the heterocyclic ring such that there is no more than one carbon atom between sulfur atoms in the heterocyclic ring so formed, wherein n is l-4 and m is 0-4, R R R and R are individually selected from the group consisting of hydrogen, alkyl of 1-6 carbon atoms, alkenyl of [-6 carbon atoms, sulfur-containing alkyl of l-6 carbon atoms, sulfur-containing alkenyl of l-6 carbon atoms, and wherein R and R and R and R respectively, can form with the carbon atom to which they are joined, a saturated, unsaturated or sulfur-containing ring of 4-8 carbon atoms, and wherein said additive is 05-15 weight percent of said composition.

3 hours 72 hours 1 b 2 b 2 b l b l b l a 2 c l a 3 a l a l b 4 b 4 c SSC-)ir groups arranged consecutively or alternatively with groups to form the heterocyclic ring such that there is no more than one carbon atom between sulfur atoms in the heterocyclic ring so formed, wherein n is l-4 and m is 0-4, R R R and R are individually selected from the group consisting of hydrogen, alkyl of 1-6 carbon atoms, alkenyl of 1-6 carbon atoms, sulfur-containing alkyl of l-6 carbon atoms, sulfur-containing alkenyl of l-6 carbon atoms, and wherein R and R and R and R respectively, can form with the carbon atom to which they are joined, a saturated, unsaturated or sulfur-containing ring of 4-8 carbon atoms, said additive being 05-15 percent by weight of the resulting composition.

4. The process of claim 3 wherein said additive is of the formula The composition of claim 2 wherein said additive is 3,3 ,6,6-tetramethyl-l ,2,4,5-tetrathiane.

6. The composition of claim 2 wherein said additive is l ,4-dicyclohexyl2,3,5-trithiolane.

7. The composition of claim 2 wherein said additive is 3,6-dicyclohexyl-l ,2,4,5-tetrathiane.

8. The compositio'nof claim 1 wherein said additive is 0.7345 weight percent of said composition. 

1. A HIGH PRESSURE LUBRICATING OIL COMPOSITION COMPRISING OIL AND AS AN ADDITIVE THEREOF, A HETEROCYCLIC COMPOUND CONSISTING OF
 2. The composition of claim 1 wherein said heterocyclic compound is of the formula
 3. In a process for improving the properties of a high pressure lubricating oil composition by adding a sulfur-containing additive thereto, the improvement which comprises employing as the additive a heterocyclic compound consisting of
 4. The process of claim 3 wherein said additive is of the formula
 5. The composition of claim 2 wherein said additive is 3,3,6,6-tetramethyl-1,2,4,5-tetrathiane.
 6. The composition of claim 2 wherein said additive is 1,4-dicyclohexyl-2,3,5-trithiolane.
 7. The composition of claim 2 wherein said additive is 3,6-dicyclohexyl-1,2,4,5-tetrathiane.
 8. The composition of claim 1 wherein said additive is 0.75- 7.5 weight percent of said composition.
 9. The process of claim 4 wherein 0.75-7.5% by weight of said additive based on the weight of said composition is used.
 10. The process of claim 3 wherein said additive 3,3,6,6-tetramethyl-1,2,4,5-tetrathiane. 